5176
BRACE AND MANTELL
[CONTRIBUTION No. 190 FROM
THE
VOL.
26
RESEARCH DIVISION,ORGANIC CHEMICALS DEPARTMENT, E. I. DU PONT DE NEMOURS AND cO.1
Hydrophobic Compounds and Polymers from Long Chain Alkanamide-Formaldehyde Condensation Reactions NEAL 0. BRACE
AND
G. J. MANTELL
Received M a y 12, 1961 N,X'-Oxydimethylenebisalkanamides were obtained by thermal or acid-catalyzed dehydration between two higher N hydroxymethylalkanamides. At a higher temperature and with acid catalysts the self-ethers split out formaldehyde and gave the hydrophobic N , N '-methylenebisalkanamides. N-Hydroxymethyldkanamides and acrylamide gave polymerizable N-( alkanamidomethyl) acrylamides. In analogy to the N,N'-methylenebisalkanamides, polymers having side chains twelve to twenty carbons long were high-melting, hydrophobic, and their side chains showed paraffinic crystallinity by x-ray analysis; those with shorter side chains were not crystalline or hydrophobic.
Reactions of formaldehyde with alkanamides were first studied in 1905 by Einhorn,' who prepared N-hydroxymethylpropanamide and related compounds. Ugelstad and De Jonge2 showed by kinetic methods that the reaction to give the N hydroxymethyl compound is reversible. We were surprised to discover that by simply heating a melt of a pure higher alkanamide such as octadecanamide and polymeric formaldehyde at, 105-llOo, the W-hydroxymethylamide (I) was formed. S o acid or alkaline catalyst was added to the mixture, as is required a t lower temperatures in solution.
laO-140° or treatment with strong acid a t a pH below 3 in solution converted the self-ether to the N,N'-methylenebisalkanamide (111), irreversibly. This sequence, I ti I1 + 111, was observed prevjously by Arbuzova' in the case of N-hydroxymethylmethacrylamide. The technical significance of this process is that it provides an efficient means for depositing the effective hydrophobizing agent M,N'methylenebisoctadecanamide in situ on a fabric or fiber ~ u r f a c e 11, . ~ itsel€, is not particularly hydrophobic. Treatment of I with aqueous alkali or with pyridine and benzoyl chloride gave the parent amide rather than 11. Lower alkyl or aryl analogs of I1 (HCHO), 110-1200 have been obtained in this way by Einhornl and RCOiVH2 -+ RCONHCHzOH f 105-110° H + , 60° later by ZigeunerlB who showed them to be true I ethers having no free hydroxyl group. RCONHCHzOCHzNHCOR + HzO Recently Petterson and Brownellg isolated a deI1 hydration product from N-hydroxymethyldoR Cii to CZI decanamide, the infrared spectrum of which was identical with those of 11. These latter workersg As heating was continued (alkali being absent), were apparently unaware of Zigeuner's work and dehydration of I to the long chain N,N'-oxydidiscarded structure I1 in favor of IV. methylenebisalkanamide (11) also occurred; removal of water drove the latter reaction to compleCi~H?3CONIICHzNCOCuH*~ I tion. Xo other products were produced, and I1 was CHZOB IV stable to several hours of heating a t 120'. Under very carefully controlled conditions I1 was also The correctness of structure I1 as demonstrated by prepared from I in nonhydroxylic solvents a t 60- Zigeuner for lower alkyl analogs, however, is 80' by acid ~ a t a l y s i s .The ~ , ~ reaction was reversed further supported by our results. We observed no by addition of water a t a pH of 3 4 . Heating a solu- absorption due to the hydroxyl group in the infrared tion of I or I1 in an alcohol other than t-butyl alco- spectrum of I1 (when free of I) and derivatives of I1 hol a t a pII of 3 4 gave the 0-alkyl ethers5n6 contain only the RCONHCHz-moiety.* Unlike I, (N-alkoxymethylalkanamides). Preparations of I1 which slowly reverts to the amide and formaldeare described in Table I. Further heating of I1 at hyde, samples of I1 have been kept several years without change. Efforts to isolate IV have failed in (1) A. Isinhorn, Ann., 343, 204 (1905). (2) J. Ugelstad aud J . De Jonge, Rec. trav. ehim., 76, the past because such structures are too unstable to be obtained directly from reaction of I with form919 (1957). (3) J. Pikl, U. S. Patent 2,509,649, April 25, 1950. (4) N. 0. Brace, U. S. Patent 2,793,182, May 21, 1957. (5) M. Englemann and J. Pikl, U. S. Patent 2,361,185, October 24, 1942. (6) J. hl. Weaver, H. A. Schuyten, J. G. Frick, Jr., and J. D. Reid, J . Org. Chem., 16, 1111 (1951). The amount of acid catalyst previously used was too much to give ethers alone We found that a pH of 3-4 wae satisfactory, however.
(7) J. A. Arbuzova, et al., J . Gen. Chem. (U.S.S.R.) (Eng. Transl.), 28, 1322 (1958). (8) G. Zigeuner, W. Knierzinger, and K. Voglar, Monatsh. Chem., 82, 817 (1951); G. Zegeuner, Kunststo$e, 41, 221 (1951). (9) R. C. Petterson and H. R. Brownell, J . Org. Chem., 25, 843 (1960).
DECEMBER
1961
51'77
LONG CHAIN ALKANAMIDE
TABLE I SYNTHESIS OF LONG CHAINN,N'-OXYDIMETHYLENEBISALKANAMIDES (11) METHODA. ACID-CATALYZED DEHYDRATION OF I METHOD B. FUSION AND DISTILLATION OF WATER
Compound I1 R CllH2.3' C17H3Sb C17HSC Ci?Hab CziHue
Yield, Method
%
A A A
-
B A
95 90
70 92
M.P.
Calcd., H
C
95-96 10&110 110-112 100-105d 111.5-112.5
-
-
74.42 75.00 74.42 -
12.48 12.58 12.48 -
C
Found, H
-
-
73.9 74.45 74.8
12.5 12.4 12.6 -
;"L'
6.5 4.82 4.60 4.82 3.87
-
70
IC' 6.0 4.48 64.45 4.6 3.92
technical grade of N-hydroxymethyldodecanamide, m.p. 102-104.5O, containing also N-hydroxymethyldecana From and -tetradecanamide. From a mixture of about 55% of N-hydroxymethyloctadecanamide, m.p. 112-114' and 45% of M-hydroxymethylhexadecanamide. From N-hydroxymethyloctadecanamide,m.p. 117"; contained about 937@of C17H35CONHCHzOH. Crude product recrystallized from isopropyl acetate; it had m.p. and infrared spectrum identical with 11. e From N-hydroxymethyldocosanamide, m.p. 119.5-120.5'; experiment done by Dr. J. Pikl. TABLE I1
N-( ALKANAMIDOMETHYL)ACRYLAMIDES AND -METHACRYLAMIDES RCONHCHzNHCOCH=CHg Yield,
%
M.P.
CHa-' n-C5H11--' n-C7H15'--C n-CiiHzs--d 12-C1&5-e
69 85 81 85 87
166-167 152.3 155.6 153.4 152.3
n-C17H3s-'*~
81
R
C
Calcd, 70 H
N
7.09 19.7 50.63 9.1 14.1 60.6 9.7 12.4 63.7 9.96 68.08 10.71 71.58 7.95 11.44 RCONHCH,NHCOC( CH?)=CHZ 11 1-113 72.10 11.55 7.65
C
Found, yo H
50.1 60.6 64.1 68.4 70.3
7.1 9.3 9.93 10.5 11.5
71 .o
11.5
N 19.7 14.0 11.9 9.4 7.5 7.3
'
From equimolar amounts of AT-hydroxymethylacetamide and acrylamide; see Experimental part for details. From N-hydroxymethylhexanamide, m.p. 55-75' (dec. on heating). From N-hydroxymethyloctanamide, m.p. 90-92". From N-hydroxymethyldodecanamide, m.p. 102-104.5'. e From a mixture, m.p. 112O, containing about 5570 of N-hydroxymethyloctadecanamide and 45% of N-hydroxymethylhexadecanamide. f Recrystallized from 2-butanone and acetone. a
aldehydelo; an excess of paraformaldehyde with 111 an excess was used of the water-soluble reactant, gave the N,N'-bishydroxymethyllo~ll and the N,N '- which could be readily removed by washing from bischloromethy111*12 derivatives under more vigor- the reaction product. Thus, N-(octadecanamidoous conditions than those which give I1 and 111 methy1)acrylamide (VIII) was prepared in 8'7% from I. yield from one mole of I and two moles of acrylw-TriJluorotridecanamide derivatives. The form- amide with hydrochloric acid catalyst.l3 Alternaaldehyde condensation products of 13,13,13-tri- tively, N-hydroxymethylacrylamide and a higher fluorotridecanamide (V) showed unexpected prop- alkanamide could be used, from which hr,N'erties. Despite the wide separation of its w-tri- methylenebisacrylamide could be extracted. Prepfluoromethyl group and amide function, N-hy- arations of VI11 and analogous compounds are droxymethyl-13,13,13-trifluorotridecanamide (VI) listed in Table 11. melted some 50' lower than the hydrocarbon analog Tetradecyl mercaptan was added with alkaline and in the presence of acid or alkali very readily catalyst in a 1,4- manner to VIIT to give a nex reverted to V. N,N'-methylenebis-13,13,13-tri- N,N'-methylenebisamide having two long chains. fluorotridecanamide (VII) could be obtained only by careful heating of VI with a trace of acid in 2butanone solution. N-(A1kanomidomethyl)acrylamides and -metha(13) Reaction of acrylonitrile and I in concentrated sulcrylamides. Acid-catalyzed condensation of I with acrglamide (or methacrylamide) gave the "mixed" furic acid [F. R. Benson and J. J. Ritter, J. Am. Chem. SOC., (1949)l gave only 111, even though these conditions N,N'-methylenebisamide in good yield. Preferably 71,4128 have been used to give AT-( benzamidomethyl)acrylamide [E. E. Magat and L. F. Salisbury, J. Am. Chem. Soc., 73, (10) J. Pikl, U. S. Patent 2,306,185, December 22, 1942. (11) M. Hunt and H. W. Bradley, U.S. Patent 2,493,068, January 3, 1950. (12) M. A. T. Rogers, U. S. Patent 2,386,140, October 2, 1945.
1035 (1951)] and methylenebispolyamides from the lower aliphatic dinitriles and formaldehyde [D. T. Mow-ry and E. L. Ringwald, J. Am. Chem. SOC.,72, 4439 (1950); E. E. Magat, L. B. Chandler, B. A. Faris, J. E. Reith, and L. F. Salisbury, J . Am. Chem. SOC.,73, 1031 (1951)j.
5178
BRACE AND MANTELL
Hydrophobic polymers and copolymers of VIII. The structure of a polymer of VI11 bears a close analogy to that of long chain methylenebisamides (111))in that a multiplicity of long side chains attached to the strongly polar methylenebisamide grouping are present. For this reason polymers of VI11 and its analogs were prepared and their hydrophobic properties determined. Those polymers of this type having side chains of twelve to eighteen carbons softened above 20O0, were markedly crystalline byox-ray analysis (paraffinic identity period of 4.17 A), and were extremely hydrophobic14; while polymers of N-(alkanamidomethy1)acrylamides having short side chains (one to eight carbons) softened above 250') showed no paraffinic crystallinity, and were not hydrophobic. Copolymers of VI11 with several common monomers were prepared (Table 111).The softening range and xray paraffinic crystallinity were affected primarily by the nature of the comonomer and, to a lesser extent, by the amount present. Copolymers containing an equimolar amount of small comonomers such as methyl methacrylate or styrene showed crystallinity and melted above 120'. All were soluble; however, those containing 2,3-epoxypropyl methacrylate or N-hydroxymethylacrylamide were readily cross-linked by heating to give an insoluble solid and in this way were irreversibly deposited on a fabric or solid surface. A copolymer containing an equimolar amount of n-tetradecyl methacrylate and VI11 softened near 100' and was not crystalline. It was apparent that the dissimilar long chain ester repeating unit interfered with side chain orientation of the amide groups. Only those copolymers containing a major amount of VI11 gave hydrophobic coatings, whereas the noncrystalline copolymer containing an equal number of long chains both of n-tetradecyl methacrylate and of VI11 was not hydrophobic.16 We conclude that oriented long side chains and a highly polar polymer chain "backbone" are together responsible for (14) N . 0. Brace, U. S. Patent 2,966,481 (1960). Analogous polymers having long hydrocarbon side chains, such aa polyvinyl octadecanoate [D. Swern, W. S. Port, J. E. Hamen, E. F. Jordan, J. W. O'Brien, and T. J. Dietz, J . Am. Chem. SOC.,69, 2439 (1940); 70, 2334 (1949); 71, 2377 (1952)], poly-p-octadecylstyrene [C. G. Overberger, C. Frazier, J. Mandelman, and H. F. Smith, J. Am. Chem. SOC.,75, 3326 (1953)], or poly-n-hexadecyl acrylate [C. E. Rehberg and C. H. Fisher, J. Am. Chem. SOC.,66, 1203 (1944); H. S. Kaufman, A. Sacher, T. Alfrey, and I. Fankuchen, J . Am. Chem. SOC.,70, 3147 (1948)] also show paraffinic crystallinity by x-ray examination [H. Mark, Annab N . Y. A d . of Sci., 57, (4), 445 (1953)l but have much lower melting points. Pol.yvinyl octadecanoate and poly-n-hexadecyl acrylate, moreover, do not exhibit a degree of hydrophobicity comparable to poly-N-(octadecanamidomethyl) acrylamide. (15) See ref. 4 and 14 for method of application to textiles and testing of hydrophobicity. It is interesting to note that VI11 (before polymerization) waa ineffective aa a hydrophobic coating on textiles, aa waa octadecanamide itself. I11 (R G&), however, waa an excellent hydrophobe.
-
VOL.
26
TABLE 111 COPOLYMERS OF N-( OCTADECANAMIDOMETHYL)ACRYLAMILIK~ Charged Polymer Mol. Softening Ratio Range
Comonomer Vinyl acetate Methyl methacrylate Styrene n-Tetradecyl methacrylate 2,3-Epoxypropyl methacrylate N-( Hydroxymethy1)acrylamide
X-Ray Cry$.,b A.
1:l 1:l
195-205' 132-140
Yes 4.17 Yes 4.17
1:l 1 :1
120-130d 90-108
Yes 4.17 Noe
20:l
196-202
Yes 4.15
10: 1
192-201
Yes 4.15
a All polymerizations done under nitrogen atmosphere in benzene solution a t 60-80" with 0.3 to 1.5y0of a,Lu'-azobisisobutyronitrile initiator. See Experimental part. Peak of sharp band; x-ray spectra taken of powder or pressed plug in North American Philips x-ray spectrometer. Analysis showed that not all the vinyl acetate waa incorporated into the polymer. Polymer precipitated in methanol from benzene solution. e Broad band only (4.10-5.0 A.).
the hydrophobic properties of these film-forming polymers. Infrared techniques proved most valuable for identifying individual compounds and determining the amount of each present in mixtures. Elementary analyses and melting points were frequently ineffective because only minor differences exist among different compounds. Characteristic absorption bands are listed in the Experimental part. EXPERIMENTAL
N,N'-Ozydimethylenebisalkammides(11). N-Hydrozymethy1octadecunamide.V An equimolar amount of paraformaldehyde was added in three portions to an isopropyl alcohol solution of technical grade stearamide (containing about 55% of octadecanamide and 45y0 of hexadecanamide) a t 60". Potassium hydroxide (10% aqueous) solution pi'as added dropwise to maintain the reaction mixture just alkaline when tested with phenolphthalein paper. After 1 hr. a t 60" the mixture was cooled to 30", acidified with acetic acid, and filtered. I, m.p. 110-11l0, was obtained in 85-90y0 yield. A Zerewitinoff determination showed 0.65y0 active hydrogen (calcd., 0.67%). The infrared spectrum was that given in ref. 9; bands a t 3.05 (NH), 3.15 (OH), 6.45 (NHCH2-) and 8.95, 9.90, 13.74, 13.94, and 14.30 p were useful for identification. Thermal dehydration of I. Equimolar amounts of paraformaldehyde and octadecanamide were heated a t 105110". Infrared spectra of known mixtures of I and I1 (see below) were used to determine quantitatively the amount of each present. A series of samples removed from the hot melt contained the following percentages of 11,the remainder b0ing I. Time (hr.) % 11
1 55
3 72
5 80
7 89
23 100
The infrared spectrum of the final product was identical to that of 11. The process was completed in 2 to 3 hr. when the water was removed under reduced pressure a t 120'. I1 was stable to long heating a t 120". Analyses are listed in Table I; a Zerewitinoff determination gave 0.37y0 active hydrogen (calcd., 0.34%).
DECEMBE:R
1961
5179
LONG CHAIN ALKANAMIDE
Acid-catalyzed dehydration of I to 11. I (390g., 1.3 moles; containing about 55% of N-hydroxymethyloctadecanamide and 45yo of N-hydroxymethylhexadecanamide, m.p. 112114') in 500 cc. of 2-butanone waa stirred, heated to 60', and made just barely acid to Congo red indicator paper by the addition of 6.0 cc. of 24% isopropyl alcoholic hydrogen chloride solution. The mixture grew thicker and 1000 cc. of 2-butanone was added during the course of the reaction. A sample was removed after 1 hr., m.p. 109-111'; 2 hr., m.p. 103-104.5'; 4 hr., m.p. 106-107'; and 5 hr., m.p. 107-108". The slurry was filtered a t 30'. The white solid was washed with a quantity of fresh cold solvent and air dried. The product weighed 350 g. (92% yield); m.p. 107.5'. An infrared spectrum of this material showed no bands attributable to I, octadecanamide or 111; bands at 3.00 (NH), 6.00 (C=O), 9.75(CHZOCH~), and 13.90 p were useful for identification. There was no absorption band a t 3.15 p when I was absent. -4comparison of absorbance values at 14.30and 13.90 p was used to calculate the relative amounts of I and I1 in a mixture of only I and 11. This method was developed by F. W. Blodgett. At higher temperatures ( 120-140') 11, in the presence of tartaric acid, or a trace of mineral acid, or at pH of 1-4 as shown on indicator paper in solution at 60-80', yielded quantitatively formaldehyde and 111; m.p. 148-149'. Stearamidomethyl alkyl ethers. The amount of acid uued in preparing AT-alkoxymethyloctadecanamides (Le., methyl, ethyl, isopropyl, n-propyl, n-butyl, phenyl ether derivatives of I) by previous workers6,Ewas critical. I n our hands, just enough acid to give a pH of 3 (about 1 to 2 drops sulfuric acid) sufficed to give the 0-alkyl ether and did not cause further decomposition to 111, which we observed when the recommended 1 m1.6pe was used. N-n-Propoxymethyloctadecanamide, m.p. 81.5-83', was prepared in this way in 70% yield by reaction of I or I1 with n-propyl alcohol. Anal. Calcd. for C&&*NO,: C, 73.95;H, 12.68;N, 4.10; mol. wt., 341.57.Found: C, 73.9;H, 12.6;N,4.10;mol. wt., 360. Infrared spectra of the various N-alkoxymethyloctadecanamides were distinctive (different from 11) and were used to identify the individual compounds. There was no absorption band at 9.75p in these 0-alkyl ethers. N-Hydroxymethyl-15,IS, IS-trifluorotridecanamide (VI ). From 5.3 g. (0.014mole) of amide V16 (mp. 103'), 0.70 g. (0.02 mole) of paraformaldehyde, 1.0 g. of potassium carbonate, and 30 cc. of benzene, heated for 2 hr. at 50°, and the benzene allowed to evaporate, was obtained 5.5 g. (100%) of VI, m.p. (sinter 64') 65-66".Attempted recrystallization of 1.0 g. in 10 cc. methanol gave 0.01 g. of the amide V, m.p (sinter 99.5")102-105", and mistures of V and VI. VI was too soluble and unstable in methanol to be crystallized. A n d . Calcd. for Cl4HzeFaO2N: C, 56.6;H, 8.83; F, 19.6; N. 4.71.Found: C. 56.6: H. 8.95:F. 20.2: N. 4.7. V I could not be'prepared in alcohol by the procedure used for I. N,N '-dlethylenebisalkanamides (111). iV,N '-ilfethyienebis tridecanamide. A mixture of 1.0 g. of tridecanamide, 10 cc. of 37% aqueous formaldehyde solution, and 1.0 cc. of concd. hydrochloric acid was heated at 68-70' for 1 hr. The white thick paste was collected on a Ruchner funnel, neutralized with ammonium hydroxide, and washed with water. The air dried solid, 1.0 g. (100%); m.p. (sinter 138") 142-146'; was recrystallized from 10 cc. of boiling isopropyl alcohol (insoluble in boiling ether or ethyl acetate); m.p. 154-154.6'; 0.70 g. Anal. Calcd. for C ~ ~ H ~ Z O Z C,N73.3; Z : H, 12.0; N, 6.32. Found: C, 74.4;H, 12.5;N, 6.2. The identical procedure gave a quantitative yield of N,N'methylenebisdodecanamide,o m.p. 148.9'. The same yield resulted from reaction of I or I1 in 2-butanone made strongly
(16) G. Gavlii and R. G. Maguire, J. Org. Chem., 1342 (1956).
21,
acid with hydrochloric acid. The infrared spectrum of I11 showed an NH band at 3.05 p, C=O a t 6.10p, N-CHIL?-at 8.86 p and bands at 13.75,13.90,and 14.40;p ; its presence in a mixture could be readily detected. N,N'-Methylenebis-18,lSliS-tri~uorotridecanamide (VII). (1) From V and aqueous formaldehyde. Reaction of 1.0 g. (0.0375mole) of V with 10 cc. of 37% formalin and 1 cc. of concd. hydrochloric acid a t 72-80' for 1 hr. gave an oil, rather then the expected high-melting solid. It waa extracted with ether, the ether solution washed with water, and the ether evaporated. The oil partly congealed to a soft semisolid which was completely soluble in petroleum ether (b.p. 3060') containing a drop or two of methanol. Various solvents gave only solution at room temperature or deposition of a soft gel. ( 2 ) From VI in Bbutanone. A solution of 0.5 g. (0.0017 mole) of VI in 10 cc. of Zbutanone waa heated to about 60' and made strongly acid by the addition of one drop of concd. hydrochloric acid. Gas evolution orcurred. The solution was kept at a gentle boil for 5 hr. After 1 hr., 3 drops of concd. hydrochloric acid waa added. The solution (10.0 cc.) when cooled deposited a soft solid (0.11 g.); n1.p. (sinter 132') 138-143.3'; a second crop of VI1 was a white soft powder (0.059.); m.p. 140.1-140.3'. Anal. Calcd. for C ~ , H ~ F ~ N ZC, OZ 60.4; : F, 19.36; H, 9.01. Found: C, 58.9;F, 19.3;H, 9.0. Its infrared spectrum was similar at characteristic points to 111. Sut sequent fractions of solid separated from solution consisted of VI1 mixed with V [0.35g., m.p. (sinter 99') 106123'1; and V, m.p. 95-100' and 97.5-100' (0.06g.). AT-(Alkanamidomethyl)acrylamidas. (a) N-( Octadecanamzdomethy1)acrylamzde(VIII) . A slurry of 300 g. (1mole) of I (n:.p. 110-111'), 142 g. (2.0 moles) of acrylamide, 0.5 g. of sodium nitrite (polymerization inhibitor), 20 cc. of concd. hydrochloric acid, and 20 rc. of water in 1.7 1. of 2-butanone was stirred a t 50-55" for 2 hr. The thick white slurry was cooled to 30"and neutralized with sodium hydroxidesolution. The solid was collected on a Buchner funnel, washed with water, and reslurried twice. After drying VI11 weighed 310 g.; m.p. 150-150.4'. A mixed melting point with 111, apossible product from this reaction, waa 141-144.5', showing nonidentity. Analyses of VI11 and homologs are listed in Table 11. The infrered spectrum of VI11 was very similar to 111, but the vinyl stretching band a t 6.15 p waa present, though poorly resolved. VI11 decolorized dilute permanganate solution and reacted with n-tetradecylmercaptan in pyridine solution with potaasium hydroxide catalyst to give N-( octrtdecanamidomethy1)12-(tetraderylthio)]-propanamide, m.p. 141-142.5'. Recrystallized from alcohol solution, it had m.p. 142-145'. Anal. Calcd. for C ~ ~ H ~ ~ O ZC,N71.90; Z S : H, 12.4;N, 4.79; S, 5.48.Found: C, 70.5;H, 11.7;N,4.8;S, 4.08. (b) Polymerization of VIII. The method described is typical for all polymerizations with this monomer alone or with other monomers. A slurry of 11.0 g. of VI11 and 250 cc. of analytical reagent benzene was heated under a nitrogen atmosphere to 80" while stirring until a clear solution was formed. A solution of a,&-azobisisobutyronitrile ABN in benzene (see table below) was added and stirring continued for 4 hr. Benzene was removed by vacuum distillation during the last 2 hr. Alternatively, the polymer waa precipitated by addition of ace-
Mol. ?6 ABN Initiator
8.8 5.1 2.55 0.64
Polymer Yield,
Intrinsic Viscosity (Chloroform 30')
Softening Range
0.15
220-233"
75 82
0.26 0.32
79
0.37
%
5180
VOL. 26
MERKER AND SCOTT
tone and collected on a filter. The residue (or filter cake) was extracted with boiling ethyl acetate and air dried. The following data Show the intrinsic viscosity of solutions to be inversely proportional to the a,a'-aaobisiobutyronitrile concentration used. (e) N-(Acetamidomethyl)acrylamide. N-Hydroxymethylacetamide was prepared from 177.0 g. (3.0 moles) of acetamide and 93.0 g. (3.1 moles) of 94% paraformaldehyde in 300 cc. of ethyl acetate a t 50-54", using 4 cc. of 25% alcoholic potassium hydroxide as catalyst. After 0.5 hr. an additional 2.0 cc. of catalyst solution was added and stirring was continued for 2 hr. A layer of N-hydroxymethylamide separated on standing overnight. Stirring was resumed while 213 g. (3.0 moles) of acrylamide and 6.0 cc. of coned. hydrochloric acid were added. After 3 hr. at 53", 4.0 cc. of coned. hydrochloric acid was added to lower the pH to 1-2. After 2 hr. the solution began to thicken, and crystalline product
[CONTRIBUTION FROM
separated. The slurry was cooled to 30", 1.0 g. of sodium nitrite was added, and the solid collected on 8 Biichner funnel. The filter cake was washed with 100 cc. of ethyl acetate and air dried; its weight wm 143.1 g. and m.p. (sinter 148") 152-156". Recrystallization from 1 :1ethyl acetate-methanol raised the m.p. to 166-161". Polymerization occurred in a heated capillary tube at the melting point. Analyses are listed in Table 11. The mother liquon gave 164 g. of less pure product (total yield 69%). (d) PolywterizaCian of N-(ace2amidomethyl)acrylamide. Polymerization occurred readily in a 10% solution in water with 1% hydrogen peroxide at 40-60". The polymer invariably formed a gel which was soluble in alcohol-water mixtures, but wa9 insoluble in acetone. The dried polymer was a white, brittle solid which did not melt a t 300". WILMINGTON, DEL.
THE
MELLONINSTITUTE']
The Reaction of Alkyl Halides with Carboxylic Acids and Phenols in the Presence of Tertiary Amines ROBERT L. MERKER
AND
MARY JANE SCOTT
Received June 1.9, 1961
The preparation of a number of esters of aliphatic and aromatic carboxylic acids and of mixed aromatic-aliphatic ethers has been carried out through the reaction of tertiary amine salts of carboxylic acids or phenolic compounds with alkyl halides. In addition to other advantageous factors, the rather large solubility of the amine carboxylates in a variety of organic solvents leads to a wide possible choice of solvent systems and reaction temperatures which are not always obtainable when employing conventional esterification methods.
The use of pyridine to discourage side reactions tory through reaction of chloromethylsilicon comin the preparation of esters from acid chlorides and pounds with various triethylamine carboxylates. alcohols has been reported by Norris and Rigby. This present paper gives examples of the extension I n a variation of this procedure Mills3 carried out of this general method of esterification to halogen this reaction in the presence of excess pyridine in an compounds in which the halogen is not activated by an adjacent carbonyl group or aromatic ring inert solvent. The preparation of some p-phenylphenacyl as well as its application for the preparation of esters through reaction of methylammonium car- mixed aliphatic-aromatic ethers. boxylates with p-phenylphenacyl bromide has been RCOOH + R'X + (R")ON +RCOOR' + (R")J'JHX reported by Drake and B r o n i t ~ k y .I~n a similar (X = ClorBr) (1) reaction Gromwell and Starks6 reported the synthesis of a-acetoxy-o-piperidinobenzylacetophe- CeHsOH + R'X + (RN)3N+ CsHsOR' (R")aNHX ( 2j none from a-bromo-p-piperidinobenzylacetophenone and triethylamine acetate in benzene solution. I n general, the procedure for conducting these More recently Moreland6has described the prepara- reactions consisted of adding stoichiometric quantition of a number of esters from phenacyl bromide, ties of the reactants either to an excess of the p-phenylphenacyl bromide, and p-nitrobenzyl chlo- particular carboxylic acid reactant or an approride through reaction with triethylamine car- priate solvent. The reaction mixture was then boxylates. refluxed or held a t some other temperature for a Concurrent with the above work, a number of suitable period of time after which the tertiary silylmethyl esters' were synthesized in this labora- amine hydrohalide was either filtered or washed (1) Multiple Fellowship on Silicones sustained by the from the reaction mixture. The products were isolated by distillation. Yields varied from about 50 n o w Corning Corp. and Corning Glass Works. ( 2 ) J. F. Norris and G. W.Rigby, J . Am. Chem. SOC.,54, to 937,. Full investigation of variables leading to 2088 (1932). optimum yields for each reaction system was not (3) J. A. Mills, J . Chem. Soc., 2332, 1951. attempted, but the results of t,he reactions carried (4) N. L. Drake and J . Bronitsky, J . Am. Chem. SOC., out proved the method to be most attractive. 52,3715 (1930). Using triethylamine as the tertiary amine in (5) N. H. Gromwell and F. 1%'. Starks, J. Am. Chena. SOC.,
+
72,4108 (1950). ( 6 ) 1%'. T. Moreland, J . Org. Chem., 21, 820 (1956).
(7) R. L. hferker, U. S. Patent 2,833,802, May, 1958.
